This application claims the benefit of Korean Patent Application No. 2000-14088, filed on Mar. 20, 2000, which is hereby incorporated by reference for all purposes as if fully set forth herein.
1. Field of the Invention
The present invention relates to an etchant composition, and more particularly, to an etchant composition for molybdenum or a molybdenum-based alloy for use in a thin film transistor liquid crystal display device (TFT-LCD).
2. Discussion of the Related Art
A method of manufacturing an electrode line, such as gate, source and drain electrodes or the like for use in a semiconductor package such as a thin film transistor liquid crystal display (TFT-LCD) device, involves a depositing technique, a photolithography technique, and an etching technique.
The etching technique includes dry-etching and a wet-etching. The dry-etching further includes plasma dry-etching, ion beam milling etching, and reactive ion etching. In wet-etching, acids and other chemical solutions are used as an etchant. In chemical dry-etching, for example plasma dry-etching, plasma is used to generate gas radicals such as fluorine radicals in order to etch any portions of a thin film that are not covered by photoresist. In physical dry-etching, for example the ion beam milling etching, an ion beam is used in order to etch any portions of a thin film that are not covered by photoresist.
Meanwhile, metals suitable for use in an electrode line, for example gate, source, and drain electrodes, include Al, Alxe2x80x94Cu, Tixe2x80x94W, Tixe2x80x94N or the like. Particularly, Al or Al-based alloy is used as a metal for the source and drain electrodes. Each of such metal materials has chemically and electrically different properties and, therefore etchant compositions suitable for each of such metal materials differ. For example, a metal layer of Al or an Al-based alloy is etched using a plasma of Cl2, BCl3, SF6, CF4, or CHF3, or using an etchant having a composition comprising phosphoric acid 72%, nitric acid 2%, acetic acid 10%, and water 16% at 40 to 50xc2x0 C.
However, an etchant solution suitable for metal materials other than Al or an Al-based alloy has not been introduced yet. When the etchant for Al is used for metal materials other than Al or an Al-based alloy, a good taper profile can not be secured. Further, in the case of using plasma to dry-etch metal materials other than Al or an Al-based alloy, production costs increase.
The current semiconductor industrial field, such as the manufacture of TFT-LCDs, requires a fast process, low production costs, good electrical characteristics, and so molybdenum or molybdenum-based alloys have been a subject of much research to be used as a material for an electrode line, such as the source and drain electrode of the TFT, instead of using Cr, Al or an Al-based alloy (for example, Mo/Alxe2x80x94Nd or Mo/Alxe2x80x94Nd/Mo).
U.S. Pat. No. 5,693,983 discloses that molybdenum material, instead of Al, is used as source and drain electrodes for a TFT but only the dry-etching technique using plasma is suggested to etch the molybdenum layer.
U.S. Pat. No. 4,747,907 discloses an etchant solution comprising ferric cyanide or ferric sulfate, but the etchant solution comprising ferric cyanide and ferric sulfate has problems in that it is difficult to treat its liquid waste, and it is also difficult to obtain a taper angle sufficient to apply to a practical LCD manufacturing process.
Accordingly, the present invention is directed to an etchant composition for molybdenum that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an etchant solution suitable for molybdenum or a molybdenum-based alloy.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides an etchant composition for molybdenum for use in a semiconductor manufacturing process, including: 5 to 20% by weight of hydrogen peroxide (H2O2); 75 to 94% by weight of water; and an additive, including a pH controlling agent.
Preferably, the hydrogen peroxide is 8 to 18% by weight, and the additive including the pH controlling agent is selected from a group consisting of ammonium sulfate, ammonium nitrate, sodium dihydrogen citrate/disodium hydrogen citrate, disodium hydrogen phosphate/trisodium citrate, or ammonium acetate.
The molybdenum layer etched by the inventive etchant solution exhibits excellent properties in taper profile, etching uniformity, etching rate as well as under-cut.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.